1. Field of the Invention
The present invention relates to an image forming apparatus that forms an image on a sheet of paper which has been transported.
2. Description of Related Art
An image forming apparatus equipped with multiple functions, which is simultaneously provided with various functions such as a printer, scanner, a copy machine and a facsimile, has been widely used in recent years. In such an image forming apparatus, a sheet of paper may be deflected to an offset position while the sheet of paper is transported to a transferring unit which transfers an image because of mechanical factors or the like in the apparatus. Thus, a line sensor which detects a positional deflection of the sheet of paper and/or registration rollers which correct deviation of the sheet of paper are/is provided upstream from the transferring unit in the transporting path of the sheet of paper. By detecting a side end of the sheet of transporting paper with the line sensor and by moving the sheet of paper by a difference between the detected side end of the sheet of paper and a position corresponding to an end of an image forming position along a width direction of the sheet of paper, a deviation of the sheet of paper along the width direction of the sheet of paper, namely, a main scanning direction of the sheet of paper on which the line sensor mainly scans is corrected.
Sheets of paper which have been met on the image forming position along the main scanning direction by the registration rollers or sheets of paper which have been fed from the same feeding tray pass through the same location in a pressure roller and a fixing belt (hereinafter, referred to as “fixing rollers”) which constitute a fixing unit so that any scratches may occur on the fixing rollers. Particularly, when using a sheet or sheets of stiff thick paper, the pressure roller or the like is subject to any scratches by means an edge or edges of the sheet or sheets of stiff thick paper. In order to prevent the scratches from occurring in the fixing rollers when the sheets of paper pass through the same location therein, a process of allowing the fixing unit including the fixing rollers to fluctuate along a direction which is orthogonal to a transporting direction of the sheet of paper has been performed.
For example, Japanese Patent Application Publication No. 2004-287317 discloses an image forming apparatus which is provided with moving means for moving the fixing unit along a width direction of the sheet of paper, which is orthogonal to a transporting direction of the sheet of paper. In such an image forming apparatus, the fixing unit can be moved along the width direction of the sheet of paper so that it is possible to prevent the sheets of paper from passing through the same location in the fixing rollers, which allows any occurrence of the scratches a the fixing unit to be avoided.